"3) Now open up the .jpg and .tga files in that directory and modify whichever ones you want to, then save them out *under a different name*. When you do, find the name of the image file you modified in the new .skin file you copied and replace the name of the original image file with the name of the new one you just saved. (When we release the model viewer, you'll be able to preview your work).

4) Now you have a .skin file that points to the new image files."

Ok...I've got as far as editing all the jpg's. How do I open the .skin file and add files to it? Is there a special program I need to open it? It's currently seen as a "goZilla skin" file.